System.Text.UnicodeEncoding 急!!!!!!!!!!!!
System.Text.UnicodeEncoding converter = new System.Text.UnicodeEncoding();
byte[] conditionExpress = converter.GetBytes(ViewState["ConditionExpress"].ToString());//这里面有+号,NND,再转过来的时候就没有+号了.
string ConditionExpress = HttpUtility.UrlEncode(conditionExpress);